272 THEORY OF RESPIRATION. 



formed, of which a part always remains dissolved in 

 the serum of the blood. 



The quantity of carbonic acid dissolved, or of that 

 combined with soda, must be equal in venous and 

 arterial blood, since both have the same tempera- 

 ture ; but arterial blood, when drawn, must, after a 

 short time, contain a larger quantity of carbonic 

 acid than venous blood, because the oxygen of the 

 globules is expended in producing that compound. 



Hence, in the animal organism, two processes of 

 oxidation are going on ; one in the lungs, the other 

 in the capillaries. By means of the former, in spite 

 of the degree of cooling, and of the increased evapo- 

 ration which takes place there, the constant tempe- 

 rature of the lungs is kept up ; while the heat of 

 the rest of the body is supplied by the latter. 



A man, who expires daily 13*9 oz. of carbon, in 

 the form of carbonic acid, consumes, in 24 hours, 

 37 oz. of oxygen, which occupy a space equal to 

 807 litres = 51,648 cubic inches (hessian). 



If we reckon 18 respirations to a minute, we 

 have, in 24 hours, 25,920 respirations ; and, conse- 

 quently, in each respiration, there are taken into the 

 blood - = 1*99 cubic inch of oxygen. 



In one minute, therefore, there are added to the 

 constituents of the blood 18 X 1-99 = 35'8 cubic 

 inches of oxygen, which, at the ordinary tempera- 

 ture, weigh rather less than 12 grains. 



If we now assume, that in one minute 10 Ibs. of 

 blood pass through the lungs (Miiller, Physiologic, 



